Brake shoe



March 11, 1930.-

W. M. DUNCAN BRAKE SHOE Filed April 2. 1928 JQT roe/var Patented Mar. 1 l, 1930 PATENT OFFICE mun: 11. Duncan, or ALTON, rumors 3m anon Application m April 2,

This invention relates to improvements in brake shoes, and has particular reference to brake shoes used on railroad vehicles, the main object being to provide a reinforcing 5 back that may be readily incorporated in the brake shoe casting, said back also having means interlocking the back to the casting.

Brake shoes are castings shaped to-conform to the tread of the car wheel, and they are secured in operative osition by a key engaging the shoe with a bra e head on the brake beam of the vehicle. The construction is such that the shoe isbridged between its ends on the head and the key passes through a centrally disposed lug on the shoe to secure the shoe to the head. As the ordinary shoe is Worn by friction in service, the casting becomes too weak to endure the strains to which it is subjected, especially in view of the manner in which it is supported, and is easily fractured, andthe broken parts displaced. Such broken brake shoes are a serioussource of danger, because they fall out of the brake head so that the means for braking the wheel is lost, and the pieces may get under other wheels and cause a derailment. Furthermore, when thebroken parts are thus scattered their scrap value is lost.

In the preferred form of my invention a reinforcing back is incorporatedin the brake shoecasting alon the back thereof, and this back has interloc 'ng means embedded inwardly in the castin and firmly uniting the casting with the baci. Whenmeinforced in this way, the casting may be fractured without falling apart, and it may continue in service until it is worn downto the steel back. It is im ortant that such reinforcing backs be very fi imly bonded to the casting by a of the shoe is practically all worn away. In my invention-the bonding means firmly interlocks the castin and the back, so that a large portion of t e bonding elements may be worn awaywithoutdestroying the bond or permitting the separation of'the casting and the reinforcingmember.

It is desirable that such a reinforcing back he roperly embedded in the cast iron when ing the casting, in order to avoid waste means that will be effective until the cast iron 1928. Serial No. 286,520.

.The back is preferably curved to conform to the rear contour of the cast iron shoe in which it is to be embedded, and I further provide a central lug, whereby the shoe'is keyed to the brake head, integrally connected to the back. All the parts of the back are 05 integrally assembled before being put in the mold. In such a construction, no cores nor chaplets are needed, and the molders time is onlyi that required to place the back in the mo With the foregoing and other objects in View, the invention comprises the novel construction, combination and arrangement of parts hereinafter more specifically described and'illustrated in the accompanying draw- 7 ings, wherein is shown the preferred embodiment of the invention. However, it is to be understood that the invention comprehends changes, variations and modifications which come within the scope of the claim hereunto appended. V

Fig. l is a rear view of a brake shoe embodymg my invention.

Fig. 2 is a side view of Fig. 1, a portion thereof being broken away.

Fig. 3 is a rear view of the reinforcing back. v

Fig. 4 is a side view of the reinforcing back.

The brake shoe herein shown comprises a shoe casting 1 and a reinforcing member or steel back 2. The front face 3 of the casting is curved to conform to the tread of the wheel. The steel back 2, which defines the rear of p the shoe, is likewise curved.

The back 2 hasa plurality of apertures 4 formed by striking tongues 5 from the back 2. (Fig. 4.) The tongues 5 are integrally attached to the back by narrow necks of metal as at 6, and the sides of each of these tongues,

tongue with the casting, o

, casting by the diverging sides of the tongues,

but an additional bond is given because the tongues point in diflerent directions, so that thecasting cannot slide off the tongues.

The rows of tongues are thus interlocked with the castin 1 and, in addition to this form of interloc the casting interlocks with the back'2 by means of bonding elements 7, formed integrally with they casting as the cast iron flows under the tongues 5 and into the apertures 4, as shown in Fig. 2.

By this means I not only prevent the separation of thecasting from the back, which is a valuable feature in the event of fracture I also minimize the occaof the casting, but

This is because the steel sion for fracture.

back is firmly bonded on one side of the shoe and thereby reinforces the shoe againstthe bending strain incurred in service. The cast iron portion-of the shoe, even when worn veryv thin, is reinforced against fracture in a simple end of the back, (Fig. 3).

and effective manner.

. Adjacentto each end of the back 2 I pro-' vide a forwardly extending leg 8, which, when incorporated in thecasting, extends from the back 2 to the face 3 of the shoe, (Fig. 2) This leg is struck up integrally from the back to leave a slot 9 extending inwardly from each Through each slot 9 and around the corresponding end of the back, extends a portion of the casting 1 to' form projections 10 at the to and bot tom of the brake shoe (Fig. 2) w ich. forms spacers between lugs on the brake head (not shown) in the usual manner;

In making the casting, the reinforcing back i I is placed in the mold and it is there supported by the legs 8 which serve as chaplets to properly locate the back in the mold be fore and during the operation of pouring the molten metal into the mold.

Centrally disposed on the back 21 mount a U-shaped loop or key lug, which extends rearwardly from the back and straddles a centrally disposed neck portion 11 of the back' -2. The terminal portions of the legs 12 of the U-shaped member are bent inwardly and under the back and welded thereto as shown projections 16 which surround the legs 12 of the U haped member (Figs. 1 and 2); The projections 16 engage corresponding recesses in the brake head (not shown) in the usual manner. i The width of-the back 2 is less than the width of the casting 1 so as to leave a shoulder 17 of cast iron along the sides of the back," (Fig. 1).

-The use of the device is thought to be obvious from the foregoing description, but 1 may here point out that, because of the novel means I employto interlock the steel back with the cast iron, the latter maybe worn practically entirely away and yet be firmly secured to the back. Thus there is very little weight of iron in the shoe when it is scrappedt Furthermore, the cast iron may be fractured. but the broken parts will not be separated from the steel back, and this security is retained throughout the life of the shoe, in fact, until the tread of the wheel contacts with the steel back itself. 4 I claim: K j

A device of the kind described, comprising a 'cast metal brake shoe provided with a rein-- forcing back, said back including a curved member at the rear face of the shoe and legs surrounded by the cast metal and extending -from said curved member to the face of the cast metal shoe to serve as chaplets in making the casting.

In testimony that I claim the foregoing I hereunto aflixm signature.

LIAM M. DUNCAN.

M13. The medial portion 14 of the U-shaped- 7 member is'parallel with and spaced from the hackto formnakey receiving passageway 15.

V A portion of the casting 1 is extended rearwardly on eachside of the neck 11 to form 

